Methods have been developed in the past to lower the content of nicotine in tobacco, given the concerns regarding the addictive nature of nicotine. Typically such methods involve chemically extracting nicotine from the tobacco prior to the usual processing required to make tobacco products. Frequently, these methods produce less satisfactory tobacco products since other ingredients in addition to nicotine are also removed from the tobacco. This adversely affects the desirable qualities of tobacco including good taste and flavor. Cultivating tobacco having reduced nicotine content has been of great interest to avoid the limitations of chemical extraction. Such methods have employed classical plant breeding and most importantly genetic modification techniques where the genetic composition of the tobacco plant is altered to produce plants that produce less nicotine. Although such methods have reduced nicotine in tobacco, they have not consistently produced cigarettes (Quest®—Nicotine Free) containing non-addictive levels of nicotine.
Nicotine is an active alkaloid compound produced primarily in the roots of tobacco plants (e.g., Nicotiana tabacum and Nicotiana rustica) and stored in the leaves and foliage. In humans, nicotine is typically ingested through the smoking or chewing of tobacco. Nicotine released from tobacco enters the body through the mucous membrane lining the mouth and lungs where it is readily absorbed into the bloodstream. The alkaloid compound has been observed to stimulate various parts of the central nervous system including the locus ceruleus and the mesolimbic center producing a feeling of well-being and enhanced mental alertness and activity in the user. After nicotine is cleared from the body, most users experience intense nicotine cravings that results in addiction to nicotine. The addictive effects of nicotine often frustrate many users who attempt to quit tobacco use.
Tobacco addiction can be prevented in most users by reducing the amount of nicotine in tobacco to levels, where during use, the blood plasma concentration of nicotine in the central nervous system is maintained below the threshold of 5 ng per ml, as disclosed in U.S. Pat. No. 5,713,376, the content of which is incorporated herein by reference. Tobacco products, which maintain the nicotine concentration in blood below this threshold level, do not produce nicotine addiction in most users. Such tobacco products typically contain nicotine at levels of about 0.01 mg per gram or less of dried tobacco.
Many unsuccessful attempts have been made to produce non-addictive tobacco while retaining many of the favorable characteristics in tobacco including good taste and flavor. For example, U.S. Pat. No. 5,158,099 teaches the use of a wetted impact barrier for reducing the content of tar and nicotine. U.S. Pat. No. 4,799,723 teaches the use of a filter consisting of a fibrous ion-exchange resin, which operates to remove ionic and carcinogenic constituents as well as nicotine and tar in tobacco smoke. U.S. Pat. No. 4,250,901 describes a chemical denaturant, to eliminate or trap nicotine and carbon monoxide. The prior art also teaches extracting nicotine from a raw tobacco product by steaming. For example, German Pat. No. 25,403 by Dr. Johannes Sartig teaches the use of superheated steam. In related techniques, U.S. Pat. Nos. 2,525,784 and 2,525,785 each teach the use of aluminum sulfate and ammonia-ethylene dichloride to separate nicotine from raw tobacco product.
There are several tobacco products, which are marketed and promoted as “nicotine-free”, however such products have often been found to contain at least measurable amounts of nicotine, which are considered addictive levels of nicotine. For example, OMNI™ and QUEST 3™ cigarettes, each of which are marketed by Vector Tobacco Inc. of Miami, Fla. to be “nicotine-free” contains as much as 0.24 (low nicotine) mg/cigarette and 0.05 mg/cigarette (nicotine-free “trace”), respectively (each cigarette contains about 1 gram of dried tobacco). The amounts contained in such low nicotine or “nicotine-free” products are sufficiently high to elevate the nicotine concentration in blood plasma to levels where nicotine is addictive in humans.
Accordingly, in view of the prior art, it would be desirable to develop methods of reducing nicotine in tobacco plants in which the tobacco product produced from such plants with a nicotine reducing treatment contains nicotine below the levels that would cause nicotine addiction in humans, and result in an improved tobacco plant, retaining the highly desirable taste and flavor characteristics typically associated with standard untreated tobacco. It would be further desirable to develop methods of reducing nicotine in tobacco plants that are commercially practical and cost effective to implement.